**6. Conclusions**

*Urban Horticulture - Necessity of the Future*

**MAB u.f.c. ml<sup>−</sup><sup>1</sup>**

> Lower than 10

Maximum 500

*of secondary importance according to CAA [41].*

*Irrigation water characteristics of urban sites.*

Altos de San Lorenzo

El Carmen

*\**

**Table 5.**

Drinking water quality

**TC NMP 100 ml<sup>−</sup><sup>1</sup>**

> Lower than 3

Maximum 3

*References levels for drinking water quality according to CAA [41].*

**130**

10 mg kg<sup>−</sup><sup>1</sup>

**Figure 10.**

close to 20 mg kg<sup>−</sup><sup>1</sup>

legumes in crop rotation. Another property that could not be improved was pH (**Figure 10a**), which was expected, since pH is one of the chemical properties of the soil that varies the least, because it is an intrinsic characteristic of the soil genesis [73, 74]. To generate a significant change in pH, some specific corrective amend-

*(a) pH: pH in water 1; 2.5 (potentiometry) [17]; (b) EC: electrical conductivity in water 1; 2.5 (potentiometry) [17]; (c) TOC: total organic carbon (Walkley and Black) [18]; (d) TN: total nitrogen (Kjeldahl); (e) EP: extractable phosphorus (Bray and Kurtz 1) [20] and (f) BD: bulk density [15] for NC: not cultivated sites and cultivated sites (C). Vertical bars indicating the standard deviation. Different letters show significant* 

**Site Count Investigation Nitrites Nitrates pH EC**

**PA in 100 ml**

100 9.2 + + 0.01 30 6.90 973

0 0 Maximum

*MAB: mesophylls aerobic bacteria; TC: total coliforms; E. coli: Escherichia coli; PA: Pseudomonas aeruginosa; +, presence; 0, absence; pH: pH in water 1.2.5 and EC: electrical conductivity in water 1.2.5 by potentiometry [17].* 

**ppm ppm μs cm<sup>−</sup><sup>1</sup>**

0 0 0.01 10 6.95 1016

Maximum 45

6.5– 8.5

Maximum 400\*

0.10

*E. coli* **in 100 ml**

With respect to extractable P [12, 34], reported that soils from this area, in their natural condition, are characterized by having low levels of extractable P (less than

). Other studies in the southern peri-urban area reported higher values,

in uncultivated soils [13, 14]. In this study, we worked with urban

ment should be applied, for example calcium sulfate.

*differences between treatments according to Tukey (p < 0.05) [32].*

Horticultural soils from the green belt of Buenos Aires are showing alarming signs of physical, chemical and biological degradation as a consequence of inappropriate management practices applied since many decades ago. The most important processes associated with soil degradation in this area were salinization and alkalization principally as a consequence of irrigation with water with high levels of sodium bicarbonate and excessive application of organic amendments. The mentioned processes are also associated with nutritional imbalances and the loss of soil structure. Soil structure is also negatively affected by the loss of soil organic matter, usually observed in intensive agricultural systems as horticulture, which is not being compensated by organic amendments. On the contrary, the use of organic amendments and inorganic fertilizers indiscriminately, without performing the appropriate previous soil analyzes, or considering the needs of the crops, generates an over fertilization that increases the risks of nutritional deficiencies and could cause environmental damage due to nutrients leaching to underground water and superficial water courses. Particularly, there is a need for research on the dynamics of phosphorus since, although this element is considered immobile, the concentrations found in the soils of the area are so high that they could exceed the retention capacity of the soils and generate important environmental impacts at the basin level. Therefore, given the problems described in this chapter, it is necessary and urgent to change the productive paradigms if the intention is to ensure food production in the most important horticultural sector of the Argentine Republic. Soil is a non-renewable natural resource, its use and management must be integrated in a long-term perspective within a sustainable development approach; within a sustainable agriculture. Agroecology gives a new approach to the agricultural system, trying to provide solutions based on the interactions of physical, biological and socioeconomic components of the systems, integrating knowledge in the local and regional level to ensure sustainable production. Urban horticulture in Argentina is being developed mainly under an agro-ecological perspective. Although production within cities covers a much smaller area and of less economic importance than peri-urban horticulture, it is a role model, generating information from multiple local experiences that can serve as a basis to change large-scale horticultural production systems. The challenges that appear in urban production systems with an agro-ecological perspective are related, among other things, to the difficulties of producing in unnatural soils. In these soils, it is compulsory to perform quality analysis, treatment and transformation to ensure a healthy and sustainable production.

The search for agro-socioeconomical sustainability and new production system paradigms are the greatest challenges of modern agriculture, which involves among other technological practices, and adequate soil management.

*Urban Horticulture - Necessity of the Future*
